Related papers: The Process " Pbar P -> E- E+ " with Polarized Ini…
The process $ \bar{p} p \rightarrow e^{-} e^{+} $ is considered in the general case of polarized initial particles. A relation between the difference of the phases of the electromagnetic form factors $G_M$ and $G_E$ in the time-like region…
We have performed numerical simulations of the unpolarized e+e- --> p pbar process in kinematic conditions under discussion for a possible upgrade of the existing DAFNE facility. By fitting the cross section angular distribution with a…
The reactions ppbar -> e+e- and e+e- -> ppbar are analyzed in the near-threshold region. Specific emphasis is put on the role played by the interaction in the initial- or final antinucleon-nucleon state which is taken into account…
We perform a global analysis of the experimental data of the electromagnetic nucleon form factors, in space-like and time-like regions. We give the expressions of the observables in annihilation processes, such as $p+\bar{p}\to \ell^+…
The data on the proton form factors in the time-like region from the BaBar, BESIII and CMD-3 Collaborations are examined to have coherent pieces of information on the proton structure. Oscillations in the annihilation cross section,…
We have performed numerical simulations of the single-polarized e+ e- --> \vec p anti p process in kinematic conditions under discussion for a possible upgrade of the existing DAFNE facility. By fitting the cross section and spin asymmetry…
We compare the existing data about electromagnetic form factors of the proton in the time-like region of momentum transfer (up to $q^2\simeq$ 14 (GeV/c)$^2$), with the corresponding data in the space-like region. From the constrains given…
We estimate two-photon exchange contribution to the process $e^+ +e^- \to p + \bar{p}$. The two-photon exchange corrections to double spin polarization observables and form factors in the time-like region are calculated. The corrections are…
An intriguing and elusive feature of the timelike hadron form factor is the possible presence of an imaginary part associated to rescattering processes. We find evidence of that in the recent and precise data on the proton timelike form…
The electromagnetic form factors $G_{\rm E}$ and $G_{\rm M}$ of the proton and neutron in the timelike region are extracted in a study of the processes $e^+ e^-\to \bar{p}p$ and $e^+ e^-\to \bar{n}n$. The reaction amplitude is evaluated…
An overview of recent data on electromagnetic hadron form factors is presented and discussed in terms of selected nucleon models in space-like and time-like regions. Model independent properties connecting scattering and annihilation…
We show that measurements of the proton's polarization in electron-positron annihilation to a proton-antiproton pair $e^+ e^- \to p \bar p$ strongly discriminate between the analytic forms of models which fit the proton form factors in the…
The electromagnetic form factors of the proton in the time-like region and two-photon annihilations into proton-antiproton are investigated. To calculate these processes at moderately large $s$ we use a variant of the Brodsky-Lepage…
New precise experimental information on $\sigma_{tot}(e^+e^- \to \pi^+ \pi^-)$ is transferred into the space-like region, by taking advantage of the analyticity. As a result a rigorous pion electromagnetic form factor behavior is obtained.…
Analyticity of nucleon form factors allows to derive sum rules which, using space-like and time-like data as input, can give unique information about behaviors in energy regions not experimentally accessible. Taking advantage from new…
Vortex states of particles - non-plane-wave solutions of the corresponding wave equation with a helicoidal wave front - open new opportunities for particle physics, unavailable in plane wave scattering. Here we demonstrate that $p\bar p$…
New possibilities of high precision measurements of hadron form factors in annihilation and scattering reactions over an unexplored kinematical region suggest a compared analysis, in view of a global description of the nucleon structure.
We update a recent dispersion--theoretical fit to the nucleon electromagnetic form factors by including the existing data in the time--like region. We show that while the time--like data for the proton can be described consistently with the…
The difference between the timelike and spacelike meson form factors is analysed in the framework of perturbative QCD with Sudakov effects included. It is found that integrable singularities appear but that the asymptotic behavior is the…
A general description of proton form factors is presented, in the whole kinematical region. The existing data and selected phenomenological models are briefly discussed.